1. Field of the Invention
The present invention relates to an optical disk and a method for manufacturing the same, and more particularly, to an optical disk with an improved information pit structure and a method for manufacturing the same.
2. Description of the Related Art
An optical disk such as a compact disk (CD) or a digital versatile disk (DVD) used as a medium for recording and/or reproducing audio or video information, as shown in FIGS. 1 and 2, includes information pits 2 recessed from a reference surface 1a, and the information is written based upon the information pits 2. The reference surface 1a corresponds to the upper surface of a land on an optical disk 1 or that of a groove. The information written on the optical disk 1 can be reproduced by an optical pickup (not shown) of a recording/reproducing apparatus, as is well known. To reproduce the information of the optical disk 1, the optical pickup irradiates a laser beam LB onto the reference surface 1a of the optical disk 1 and detects the amount of the laser beam reflected from the optical disk 1. Since the irradiated laser beam LB is scattered at the portion corresponding to the information pit 2, the amount of the laser beam reflected toward the optical pickup is reduced. The reduction in the amount of the laser beam LB occurs in all the information pits 2, and the information of the optical disk 1 can be reproduced by detecting the change in the reflected light amount in the information pit 2. Thus, the less the amount of the laser beam reflected from the information pit 2, the better the information reproduction characteristics. It is generally known that the amount of the light reflected from the information pit 2 becomes a minimum when the depth (d) of a bottom surface 2a of the information pit 2 is set to .lambda./4n (.lambda.: the wavelength of the laser beam and n: refractive index of the optical disk).
In the conventional optical disk, to adjust the depth of the information pit appropriately, when manufacturing a master board for manufacturing the optical disk, the thickness of a photoresist layer must be consistently controlled. Also, even if the appropriate depth of the information pit is adjusted correctly, the laser beam reflected from the bottom surface of the information pit may be detected by an optical pickup, which has an adverse effect on the information reproduction characteristics of the optical disk.